ProSoft Technology 5202-DFNT-MCM4 - Manual (Page 35)

Serial Port Modbus Error and Status Data MCM ♦ ProLinx Gateway
Driver Manual Modbus Master/Slave
ProSoft Technology, Inc.
Page 35 of 80
October 16, 2009
4.2.2 Slave Port: General Port STATE and COMM STATE Status
In addition to the port status information stored in the gateway database memory,
as already mentioned, which are also shown in the diagnostic screens, there are
two additional port status parameters that are not available from the database.
The status values, Port STATE (highlighted in yellow) and Port COMM STATE
(highlighted in orange), can be found only though the diagnostic menus under
"Communication Status" for a port, as shown in the following graphic.
These status values are state registers. They are used as 'scratchpad' areas by
the operating firmware to keep track of the current logical state of activities on a
slave port. These state registers are constantly changing as the gateway
progresses through the various stages needed to process communication on the
serial ports. This processing happens faster than can be followed, unless a port
error causes the value to remain constant for some noticable length of time.
The diagnostic screen displays are 'snapshot' type screens; that is, they display
the current value at the time they are called but do not continue to automatically
update the data displayed. They are not live-data screens. Therefore, to see a
change in STATE or COMM STATE, you must repeatedly call the screen by
pressing the appropriate menu key to have the screen refreshed. Depending on
the refresh timing you may or may not see a change in the displayed values
everytime you call for an update.